The corner corrosion problem of wheel cap sections has been badly in need of improvement. For a cast wheel having the front side not machined, burrs at the cap section are located at the joint area of machining and casting and distributed circumferentially, and it is difficult to ensure consistency and no residue when the burrs are removed. Particularly for a polished product, if the burr removing effect is not ideal after machining, it is difficult to polish corners in the polishing procedure, the coated corner film is not thick enough, and corrosion is finally caused.